How to Check the Second Generation DSM ECU for an EPROM

These instructions only apply to cars with Mitsubishi-equipped engines.

[NOTE!]Technomotive does not assume any responsibility for the use of this document or its information.

Here is a handy table which you can print out to record your ECU information. As long as you have your ECU open, you might as well record this information so you will have it available if you order an ECU upgrade.

Car Year  
Car Model  
Engine Type 1.8l / 2.0l / turbo
Smog control CA or similar / Federal
Transmission Auto / Manual
Transaxle FWD/ AWD
ABS equipped YES / NO
ECU part number  
EPROM Code#  
Microcontroller Code #  
R255 YES / NO
R256 YES / NO
Board #  

Figure 1

Figure 2
Driver's side
  1. Locate the ECU. Figure 1 shows the ECU in the center console, underneath the radio. Note that this figure has a slight error - the ECU actually stands vertically. Figure 2 shows this fact (your view might be slightly different depending upon stereo equipment options installed). To get to the Figure 2 view, you will have to remove the center console carpeted kick panels from both the driver and passenger sides.
  2. Remove the ECU. There are four plug connectors (encircled in green in Figure 2) which must be removed. There are three bolts that hold the ECU in place. One is circled in yellow. There is also a bolt that you can't quite see since it appears sideways in this photo. The area it occupies is located inside the yellow rectangle. There is yet another bolt on the passenger side mounted similarly. When removing the ECU, you might have to wiggle it around a bit - there are other wire harnesses in the area, making for a tight squeeze.
  3. Open up the ECU. There are four screws on the outside of the case. Be absolutely certain that you are using the correct size Phillips screwdriver. For some reason, they put tons of torque on second generation ECU screws. The wrong size head will lead to stripping the screw heads.

Figure 3
  1. Check for external EPROM. The EPROM in Figure 3 has a red circle on it. If your ECU looks similar to Figure 3, but is missing this EPROM, any ECU upgrade will involve the use of a daughterboard which plugs into where the microcontroller chip is.
  2. Gather part numbers. The EPROM in Figure 3 has an EPROM number of EB23C (circled in red). The microcontroller number is circled in green. We are interested in the number of the form EXXX. On this particular ECU, the number is E100. Ignore the numbers "MH6311" and "76C55T" - these are internal Mitsubishi part numbers only. At the top of Figure 3, there is a board revision number (circled in blue). This ECU has a rev number of JE331B677C. Your number should be close to this one, perhaps varying in the last letter. There is also an ECU part number stamped on the ECU harness connector (circled in purple). This ECU has part number 1672B.
  3. Check the ConfigID. There are two configuration-identification resistors. The existence or absence of these resistors let the ECU know things about the engine it will be controlling. In this way, Mitsubishi can build one ECU, solder one of four different resistor combinations in, and re-use that ECU for four different engine packages. These resistors are R255 and R256 (circled in yellow in Figure 3). Please note whether or not there are resistors soldered in at those two locations.
  4. You are done! Reverse the above steps to re-install your ECU.

©1996-7 Technomotive
September 13th, 1997